"The planet . . . was scarcely any larger than a house!"

July 21, 2010 11:00 PM

The Planetary Society's Emily Lakdawalla has prepared a scale image of every asteroid and comet ever visited by a spacecraft.

The Planetary Society's blog is always a treat but The Planetary Society's website offers up other content too. You can explore various Society projects, extrasolar planets, various spacecraft, there's Planetary Radio, SETI, and a wealth of other content.

posted by IvoShandor (15 comments total)

Pic is cool. Some big old rocks! I wish they'd have superimposed the image over a map or something for a better intuitive grasp of the actual sizes. Being from the USA, I tend to have a better idea of things in miles rather than kilometers.
posted by InsertNiftyNameHere at 11:23 PM on July 21, 2010

Excellent post, and excellent image. Reminded me of why I loved Hayabusa, and I just spent the last five minutes exclaiming to my partner about how awesome ion engines are.
posted by Made of Star Stuff at 11:35 PM on July 21, 2010

How bout this: the average city block is about 1/8 mile, or 0.2km, a little bit smaller than the smallest asteroid on there.
posted by chaff at 11:38 PM on July 21, 2010

How bout this: the average city block is about 1/8 mile, or 0.2km, a little bit smaller than the smallest asteroid on there.

That's quite helpful. Thank you.
posted by That's Numberwang! at 11:47 PM on July 21, 2010

I'm confused.

If this is "every asteroid or comet" ever visited, where is Giacobini-Zinner for example?
posted by vacapinta at 1:42 AM on July 22, 2010

This graphic only includes asteroids, the op is mistaken.
In case there is confusion, comets are objects with an orbit that varies significantly in distance to the sun, hence the tail of volatile materials when they get close enough to be heated up by it, while asteroids mainly move in stable circular orbits somewhere between Mars and Jupiter.
Another definition just goes by visual impression; Comets have a tail/halo. Asteroids don't.
posted by Catfry at 2:06 AM on July 22, 2010

If this is "every asteroid or comet" ever visited, where is Giacobini-Zinner for example?

I think I can answer that. I seems you are technically correct. The blog post says: "The total of four comets and nine asteroid systems (including ten separate bodies) that have been examined up close by spacecraft

That's probably even too vague. I know Giacobini-Zinner and Grigg-Skjellerup were visited by spacecraft but there weren't images taken of either one. The former because the spacecraft carried no camera and the latter because the craft's camera was destroyed. I suppose that's probably the reason. Sorry for the confusion.
posted by IvoShandor at 2:07 AM on July 22, 2010 [1 favorite]

Dude, that's embarrassing. It actually says asteroids AND comets. Hm. Well I'm wrong and don't know what's going on.
posted by Catfry at 2:08 AM on July 22, 2010

chaff: "How bout this: the average city block is about 1/8 mile, or 0.2km, a little bit smaller than the smallest asteroid on there."

Nice to know this now. Many thanks!
posted by InsertNiftyNameHere at 2:25 AM on July 22, 2010

Just one year until Vesta!
posted by gubo at 6:12 AM on July 22, 2010 [1 favorite]

about 1/8 mile, or 0.2km

That's quite helpful. Thank you.
posted by That's Numberwang!

Indeed. Let's rotate the board!
posted by unregistered_animagus at 6:39 AM on July 22, 2010 [2 favorites]

Those are only the ones they want you to know about.
posted by blue_beetle at 8:23 AM on July 22, 2010

Catfry: Halley is certainly a comet, so there's at least one on there.
posted by Guy_Inamonkeysuit at 8:25 AM on July 22, 2010

Yeah, I don't know what I was thinking.
posted by Catfry at 8:47 AM on July 22, 2010

all four in that corner are comets (borrelly, tempel, wild, halley)...the tails are just very underexposed in this image so you can see the main body instead of just a big white blur.
posted by sexyrobot at 9:43 AM on July 22, 2010